Jac3510 wrote:neo-x wrote:I wanted to highlight this part, as I think it is not a required correlation that oxygen be a necessary bi-product of hyper-evolution during any bleak atmospheric period of time. And life can be very different elsewhere. Composed of different chemicals and forms and shapes and sizes. It can happen in some instances but it is not the standard way, that evolution has to follow in order for life to grow.
As I said before, oxygen producing life is just another form of life which thrived under certain settings. Saturn's moon Titan has lakes of methane and ethane, who knows if microbial life exists there or not. It is entirely possible if not likely.
So let's stick with this, because I think this might be what has been interesting me.
It seems to me that we know that the great oxygenation event presumes the evolution of oxygenic photosynthesis, which is, of course, the common form in most life today. But since the early atmosphere was basically anoxic--and since that seems to be the case with all early atmospheres because that's just the way planetary formation works (atmospheric oxidation, again, requires oxgenic photosynthesis, which presumes an oxic atmosphere)--we would assume that lifeforms built around anoxic photosynthesis necessarily and always comes first in
any form of abiogenesis.
If I'm mistaken about that, I'd like to see some sources explaining how an early atmosphere could be oxic
without the existence of oxygenic photosynthesis. But on the assumption I've understood this correctly, then I want to go back the the original question I asked about the article. The evolution of life from non-life in less than 200 million years isn't
just finding a chemical pathway like you've been talking with Rick about. It means that path necessarily goes through the evolution of anoxygenic to oxygenic photosynthesis. In other words, the 3.7byo stromatolites don't tell us so much about the origin of life per se (as I'm sure you know) as it does how early we get to what I'll call a third stage: the first stage being the evolution (to use the word loosely) of a chemical environment that allows the self-formation of the building blocks of life; the second being the evolution (to use the word a little less loosely) of obligate anaerobes and thus anoxygenic photosynthesis; and the third being the evolution of our stromatolites and their related organisms.
Jac, let me see if I read you correctly here, are you saying that for oxygenic photosynthesis to happen you need an oxic atmosphere to begin with? I'm sure you read that Oxygen was a byproduct and started out as such?
I don't necessarily disagree with you in what you describe as the 3 stages. This process must have been present in a step by step way.
However where you think it is highly unlikely by this alone, there are good reasons to consider, besides extreme uv radiation, that accelerates mutation. One more factor was that oxygen based life, when it started had inherently a faster metabolism than reductive metabolism which life before it had. Oxidative metabolism was faster, which inturn suggested that more energy could be produced which meant, more chances of growth survival, mutations and diversification. That is one advantage that oxygen based life forms had and that might have explained the "explosion" of oxygenic life forms on earth.
So, in my non-professional opinion, 200 million years is really fast for that to happen. I suppose a theistic evolutionist could claim in a god-of-the-gaps fashion that it worked because God intervened at the crucial moments. Or we could suggest a natural mechanism. In light of the latter, you've suggested a hyperevolution based on the presence of a lot of UV radiation and other such things. Fine. Let's take that as a possible mechanism. It seems, though, that my original question stands, even in places like Titan. After all, the move from anoxygenic to oxygenic photosynthesis in such a quick and dramatic fashion suggests this isn't so much of an accident as it is just the nature of evolution itself. Sort of like chemicals will self-assemble into certain pieces that could form the building blocks of life, so these conditions seem like they'll just give rise to the evolution in question. If not, how do we explain not only the evolution that happened here but the fact that it happened in such a quick and decisive manner?
If we see our immediate environment, like Jupiter, venus, Saturn, it's hard to imagine such barren planets as lifeless. For one thing, they are atmosphere-less or too atmospheric. The rise of oxygenic lifeforms on earth built the ozone and thus stopped the intense uv radiation that had before then scorched earth and the life forms there. And if you look at it that way, it is understandable how that quick-fast or hyper-evolution scenario was no longer the case or norm after we had the ozone, and after that evolution took a slow road and billions of years to reach its present shape, it was no longer fast enough, for even though now creatures had a faster metabolism, they lacked the higher amounts of radiation to cause mutations as fast as before.
If the earth hadn't formed an atmosphere, life would have never reached a sustainable state. Constant mutation is also not good for life, it can happen for a short period of time, and by short, I mean on the cosmic scale short, to be viable. But constant rapid mutation doesn't give time enough for life to stay and grow in a steady fashion. So if the hyper-evolution period occurred, it had to end rapidly in order for life to survive. But I also propose that it only happened because the uv radiation allowed time enough for as many mutations necessary to get to cyanobacteria which produced oxygen as a byproduct. Had that one mutation been missing, even if several predecessors of that mutation may have had survived, the atmosphere would not have formed and thus life here would be very difficult or different than oxygenic life.
If it isn't clear, I'm appealing to something like a weak anthropic principle--it couldn't be any different because if it were, we wouldn't be here. Because we are, it was that way, and it was that way by necessity. It all seems very reasonable to me. The problem is with places like Titan. So perhaps the reason it doesn't happen there is the shear distance from the sun, but I'm not sure that's ultimately going to cut it. The atmosphere is certainly anoxic, but that doesn't mean that there is no oxygen. Just like Mars, it turns out there is a lot of oxygen on Titan. It's just frozen. And since the methane oxidization process is an efficient way to get energy, it would seem "natural" (to this non-professional) for oxygenic photosynthesis to evolve just as easily there as it did here--especially, again, given how quick it happened and what that suggests about the nature of the chemical pathways, of the evolution itself. And while you could perhaps argue that the process was sped up on earth (perhaps because we are closer to the sun), the fact remains that Titan, to use your example, is still billions of years old. I mean, Saturn is about 4.6byo, so Titan couldn't be too far behind that. I've not seen a number (I haven't looked much), but say it formed 3byo . . . if we got molecules to oxygenic photosynthesis (in massive quantities no less) in less than 200 million years, we ought to at least see anoxygenic photosynthesis on Titan, right? And why not Mars? And other places?
I get your point and I think I understand how you are seeing it. From my point of view, distance from sun, is very important plus what kind of atmosphere you have. For example take Titan, it has a dense atmosphere and thus it may be blocking UV radiation which means that it can't exactly replicate what happened on earth. The uv radiation caused mutations on earth.
Maybe Titan once had life but then it died down, maybe it has life frozen. or it is still there. But for steady evolution to happen, you need mutation plus factors which ensure the survival of life. On earth we have had over a dozen of extinction events, 5 of which are major ones, and one of them almost wiped all life from earth.
So life that needed atmosphere, in its absence would die down. I could imagine Mars having life but with an atmosphere which is 100 times less dense than earth life would not sustain. There would be either too much mutation, or change or very little, in both cases, not good for sustaining life.
After all, the move from anoxygenic to oxygenic photosynthesis in such a quick and dramatic fashion suggests this isn't so much of an accident as it is just the nature of evolution itself. Sort of like chemicals will self-assemble into certain pieces that could form the building blocks of life, so these conditions seem like they'll just give rise to the evolution in question. If not, how do we explain not only the evolution that happened here but the fact that it happened in such a quick and decisive manner?
The highlighted part is what I agree and disagree with. Yes, if you have the right conditions chemicals will self-assemble, but you will rely on many different factors for sustainable life to be present.
I think it is nature of evolution that it will mutate and produce life and also produce extinction. It is one part that is often left unsaid. Evolution
naturally would not always produce molecules to man. Evolution will produce mutated variations, it then depends on the organism if its mutation helps it survive in the given conditions that helps it adapt or go extinct. If an organism, mutates too much without adapting to its natural conditions in a steady way (means it keeps changing biologically and chemically), it dies, like anoxic life; if it mutates too little and doesn't adapt in a steady way, it again dies. Evolution thus happens on the edge of extinction, go overboard with it and you end up dead, go under and you again go dead. That is why evolution only happens successfully when organisms get the mutation which helps them adapt. That is why 99% of all life on earth has gone extinct, only the handful remained, only those which had a mutation that helped them survive.
In short, I agree with you that life can arise in a lot of different planteray formations, but will it sustain, that depends on lots of things and even though life may arise in the same way anywhere, there is no guarantee that it will survive too.
Distantly related note, I explicitly appealed to the WAP in the post above. If I've understood the evidence correctly, I wonder if a TE isn't better off suggesting that the evidence as we have it actually more strongly warrants a SAP--that is, that there is some mysterious principle we don't yet understand would somehow compel the universe to promote or ultimately produce self-conscious life. A nice thing about such a theory is you would no longer need to appeal to multiverses and other such ideas to explain away some of the statistical problems we get ourselves into (and that serve as the cornerstone, for good reason (though often dismissed by non-theists), of fine-tuning arguments for God's existence) when discussing these matters.
The appeal to multiverse is just a theoretical construct to solve the problem of a universe arising the way it did.
And my own view is that our universe should have many many forms of life, sustainable life, because there is so much out there that we don't know and can see, not yet anyway that to think that among hundreds of trillions of stars and planets we alone harbor life is mathematically weak. That you are calling evolution "quick and decisive", you'll see it in many more places. Just not in our own solar system and that too because of a myriad of reasons.
And since the methane oxidization process is an efficient way to get energy, it would seem "natural" (to this non-professional) for oxygenic photosynthesis to evolve just as easily there as it did here--especially, again, given how quick it happened and what that suggests about the nature of the chemical pathways, of the evolution itself.
Only if it gets a mutation like that.
You know the DNA molecule is a self-replicating molecule. The problem is that often there are errors, in copying, and that what gets you a mutation, the rate of change of these mutations accelerate if such molecule has uv radiation exposure. However, the mistakes are random. The molecule doesn't make mistakes in the same pattern either. So it is really not necessary for it to produce the mutation on earth and mars and titan even if all these places had the exact same biological, or chemical composition or to put it in simpler terms, had there been three identical earths and evolution happened on all three, the results would differ even in identical, and I mean identical to the dot, conditions. Because the molecule will make mistakes in reproduction regardless of external influences such as radiation (although it produces mutations too). It's internal copying errors would again be random and over time plenty.
So while life will happen, it won't produce the same results. There is no "standard" path of evolution when it comes to self-replication and the mutations that occur along with it.
So I now this can sound like an argument against abiogenesis. I don't mean it as such. I really want to know how this data fits into an evolutionary viewpoint. It just seems to me that the nature of life itself painted by the evidence is pretty astounding. So I'm curious how you are seeing it. Thanks again!
I am a non-professional again and I am not sure if what I wrote made much sense. Let me know if I can clear it up further if needed. To be precise I agree with life arising in a lot of places but to me it doesn't follow that planetary formations, even if they start the same way, will end up with the same form of life or the processes that we see on earth, they won't because of the nature of the self-replicating molecules like the DNA, making non-coherent mistakes/mutations, missing out on data and having copying errors, sometimes for no reason at all.
Edit
I think the difference between your view and mine is that you are, perhaps, viewing this in a linear way. I am not.
To put up a weak analogy to what I said earlier, consider a set of pool balls. Now if you hit a ball on the pool table, in a certain direction, by following the laws of Newtonian physics, you can predict the trajectory of the ball far into the future, where it will hit, where it will rebound, where it will hit next based on the angle of the rebound so on and so forth. you can, in theory, predict it infinitely. but in reality, your prediction will end up wrong on the 3rd or 4th rebound. Why? because tiny imperfections in the surface of the pool table, small indentations on the ball or on the railings will all mount up, getting the ball skewing off course slightly at first and then ending way differently than the original spot you had in mind if it had the energy to go on for say 100 rebounds. It will never land on your predicted trajectory in the end because of those tiny imperfections, dents, problems.
One small change at a base level will have consequences so profound that the end result will be far off trajectory. And that is also true of biological-chemical systems.
I will go as far as to say that if you reversed the clock on planet earth and restarted the biological process all over again with the exact same conditions as we had, the outcome will be vastly different.
Thank you too.
